The energetics and electronic structure of a ${\mathrm{C}}_{60}$ monolayer on Cu(111) surfaces have been investigated thoroughly via large-scale first-principles density functional theory. The calculated adsorption site and orientation of the molecule, and the work function are in excellent agreement with experimental observations. We find that the translational motion of ${\mathrm{C}}_{60}$ across Cu-Cu bonds can be barrierless, while a $360°,$ on-site rotational motion is subject to a barrier of 0.3 eV. A close to ${0.8e}^{-}$ charge transfer per molecule from the surface to the ${\mathrm{C}}_{60}$ monolayer is determined, which provides important insights into a number of experimental measurements. Our analysis also indicates that the transferred electrons are localized in a plane between the molecule and surface, and that the bands near the Fermi level are highly hybrid between the surface and the molecule, reflecting a strong metal-fullerene coupling. Furthermore, an analysis of the dipole moment clarifies the puzzling phenomenon regarding the work function.

• Received 3 September 2003

DOI:https://doi.org/10.1103/PhysRevB.69.045404